Well, thank you for the kind words. I'm glad that my build thread can be of use for someone.
I knew that I was using an AT screen from the start, so the space behind the screen this just made sense. It was designed to hold the speakers and sub. Holding the pole was a bonus. I have to say, that the pole did present a problem that we were able to overcome quite elegantly. The angled walls did present a challenge for the acoustical plan, but BPape worked around it quite well. There is another member of this forum with the same house plan that I have (his is in another town). By chance, we both put our theaters in the same part of the house. His is flipped...his screen is where my back wall is. We did this without knowing. I met him at his theater open house and that's when I found out we had the same plan. His handle on here is mmmkam. Check out his finished theater too.
If I were doing this over again, I'd use the design service (see the sticky at the top of this forum). They will be able to help you plan out a great space, including an acoustical plan. The design alone is well worth the price. Check it out...the folks who do it are pros!
I don't see any problem with taking some of the space that would be dedicated for behind the screen for use as a storage area accessible from the outside. I would expect that ou need at least 28" between the screen and the back wall for speakers. 36" would be better, depening on the size of your speakers. The space between the outside and inside should be separated by a wall and treated accordingly.
Start a build thread, and post a picture of the space and your proposed plan. Some of the regulars here will be able to chime in and help you figure out some alternatives or provide some pointers.